| Click for the Finfacts Ireland Portal Homepage |

Finfacts Business News Centre

News Main Page 
 
 News
 Irish
 European
 International
 Asia-Pacific Business Week
 
 Analysis/Comment

RSS FEED


How to use our RSS feed

 
Web Finfacts

Welcome

Finfacts is Ireland's leading business information site and you are in its business news section.

We provide access to live business television and business related videos from: Bloomberg TV; The Wall Street Journal; CNBC and the Financial Times. Click image:

Links

Finfacts Homepage

Global News

Bloomberg News

CNN Money

Cnet Tech News

Newspapers

Irish Independent

Irish Times

Irish Examiner

New York Times

Financial Times

Technology News

 

Feedback

 

Search

News : International Last Updated: Dec 19th, 2007 - 13:17:15


650,000 year old ice signals link between greenhouse gases and climate change
By Finfacts Team
Nov 27, 2005, 17:56

Email this article
 Printer friendly page

Drilling tower at Dome Concordia. Photo © A. Fornet/IFRTP - The single most important source of information about past climate change and the associated composition of the atmosphere are the two large ice caps of Greenland and Antarctica. Analysis of ice cores is therefore the most powerful means we have to determine how climate has changed over the last few climate cycles, and to relate this to changes in atmospheric composition, in particular to concentrations of the principal greenhouse gases - CO2, CH4 and N2O (carbon dioxide, methane, and nitrous oxide).
Shafts of ancient ice extracted from Antarctica's frozen depths show that for at least 650,000 years three important heat-trapping greenhouse gases never reached recent atmospheric levels caused by human activities, scientists are reporting today.

In an article in the journal Science titled Tiny Bubbles Tell All, Edward J. Brook says that during the past 200 years, humans have caused a remarkable change in the levels of several atmospheric greenhouse gases. We know this from direct measurements that started in the latter half of the 20th century, but for earlier times we rely on tiny samples of the atmosphere trapped in polar ice. Coring the polar ice sheets provides access to these samples and allows us to place modern changes in the context of long-term natural cycles in greenhouse gases. Until recently, the longest of these ice core records (from the  Russian research station  Vostok Station in Antarctica) extended back 440,000 years. Now, the window into the past has been extended an additional 210,000 years.

Since 1997, the oldest ice available for analysis was that from the Vostok, Antarctica, ice core, which extends back to 420,000 years ago and covers four complete glacial cycles. A new ice core from the  European Program for Ice Coring in Antarctica, (EPICA) Dome C site in Antarctica now extends back to an age of 740,000 years or more. Two reports present data on the composition of the atmosphere between 400,000 and 650,000 years ago, an interval soon after glacial cycles switched from a dominantly 41,000-year period to the dominantly 100,000-year period that occurs today.

Brook says that two basic messages are apparent in this extended history of the atmosphere. First, even with this longer perspective, the modern atmosphere is still highly anomalous. At no time in the past 650,000 years is there evidence for levels of carbon dioxide or methane significantly higher than values just before the Industrial Revolution. Second, the covariation of carbon dioxide and methane with climate, strikingly evident in the Vostok record, follows essentially the same pattern in the earlier time period. The muted climate cycles are accompanied by equally muted cycles of carbon dioxide and methane (see the figure). This relationship reinforces the view that the large-scale cycles in Antarctic temperature have global importance, and that climate and greenhouse gas cycles are intimately related.

The long view.The greenhouse gas (CO2,CH4, and NO2) and deuterium (À D) records for the past 650,000 years from EPICA Dome C and other ice cores,with marine isotope stage correlations (labeled at lower right) for stages 11 to 16 (2, 3). À D, a proxy for air temperature, is the deuterium/hydrogen ratio of the ice, expressed as a per mil deviation from the value of an isotope standard (4). More positive values indicate warmer conditions. Data for the past 200 years from other ice core records (20–22) and direct atmospheric measurements at the South Pole (23, 24) are also included. Source: Science

Levels of carbon dioxide have risen from 280 parts per million two centuries ago to 380 ppm today. Earth's average temperature, meanwhile, rose about 1 degree Fahrenheit in recent decades, a relatively rapid rise. Many climate specialists warn that continued warming could have severe effects, such as rising sea levels and changing rainfall patterns.

Brook says for nitrous oxide, the picture is slightly less clear. The record is not complete, making it difficult to judge how or whether the amplitude of 100,000-year cycles changed with time, and anomalous levels of nitrous oxide appear to be related to high levels of dust in the ice.

Skeptics often dismiss the rise in greenhouse gases as part of a naturally fluctuating cycle. The new study provides ever-more definitive evidence countering that view.

Today's  rising level of carbon dioxide already is 27 percent higher than its peak during all those millennia, said lead researcher Thomas Stocker of the University of Bern, Switzerland.

"We are out of that natural range today," he said.

RELATED:

Manufacturing offshoring lowers US greenhouse gas emissions

Arctic ice cap may melt by Summer 2070


© Copyright 2007 by Finfacts.com

Top of Page

International
Latest Headlines
Markets News Wednesday: Stocks deep in red ink across the globe: Asia-Pacific and Europe slump following grim day in New York
Apple launches MacBook Air - the world’s thinnest notebook
Europe suffered a slowdown in labour productivity in 2007; Rich countries face struggle to achieve rises in living standards
Wednesday Newspaper Review - Irish Business News and International Stories
Intel reports 51% rise in Q4 2007 net income but cautious outlook for 2008 sends shares plunging 14% in after-hours trading
Markets News Afternoon: Citi rains heavily on markets in Europe and US - Dublin plunges almost 4%
US retail sales fell in December signalling that consumer spending is under strain; Producer/Wholesale prices rose 6.3% in 2007 - the highest since 1981
Citigroup reported Q4 2007 loss of $9.83 billion; Write-downs and increased credit costs were a massive $22.2 billion
Markets News Tuesday: Citi bad news awaited; Markets fall in Asia-Pacific and Europe; Dollar up from near record low against Euro; Gold price over $900
Hong Kong and Singapore again head Index of Economic Freedom; Ireland gets third ranking
Tuesday Newspaper Review - Irish Business News and International Stories
US Hedge Fund Index shows return of 11.15% in 2007 - More than double the S&P 500 performance
Markets News Afternoon: Stocks rally in US and Europe boosted by positive fourth quarter data from IBM and SAP
IBM reports strong fourth quarter preliminary earnings boosted by Asia, Europe and Emerging Countries
Markets News Monday: Start of US fourth quarter earnings season has investors worried about how banks and brokerages have performed
Monday Newspaper Review - Irish Business News and International Stories
US study says Environmental Factors shaping New Global Economy
Markets News Afternoon: Report say Merrill Lynch will announce $15bn loss next week; Stocks down in US and Europe - Dublin market up; Gold tops $900
US trade deficit increased to $63.1 billion in November
OECD Composite Leading Indicators signal a downswing in all major OECD economies